Douglas Hughes' family have lashed out at the army for failing to come clean on his suicide in Afghanistan. Photo / CPL Brad Hanson

Twenty armed forces personnel have been killed in the past three years - with a number of deaths linked to training failures and gaps.

There have been a total of 34 deaths over the past decade, according to information released under the Official Information Act.

Most occurred after 2010 as the security situation worsened in Afghanistan.

The rise in deaths happened over a period in which the Defence Force lost many experienced staff.

Those killed include Corporal Douglas Hughes, whose family have lashed out at the army for failing to come clean on his suicide in Afghanistan.

The corporal was one of three soldiers who killed themselves last year, information from the Defence Force shows.

He was sent to Afghanistan following scaled-down deployment training, which reduced the amount of advice on coping with stress.

Training failures were highlighted in a number of other deaths:

The inquiry into the 2010 Anzac Day crash which killed three people found safety and training failures.

The inquiry into the 2010 death of Lieutenant Tim O'Donnell found basic failures in training for personnel sent to Afghanistan.

The report into the 2011 death of Private Kirifi Mila highlighted training issues.

The 2012 pre-deployment training report into the detachment to Afghanistan that lost five troops in combat.

The court of inquiry report into Tim O'Donnell's death linked resourcing to deployment training and called for a review. It said training was not guided by current tactics and the situation in Afghanistan. It also stated the "operational level of capability" training was "not resourced to prepare deploying personnel".

An NZDF spokesman confirmed that the inquiry into Lieutenant O'Donnell's death recommended "the approach to training and preparing NZDF personnel be reviewed".

But he said a senior commander who signed off on the inquiry report considered these areas were part of "business as usual" reviews and highlighted for action "training on specific items of equipment to be used in Afghanistan".

Labour defence spokesman Phil Goff said Corporal Hughes' deployment to Afghanistan had its training cut from five weeks to three because of commitments to the World Cup. He would have expected Defence Minister Jonathan Coleman would have signed off on the shortened training period.

Dr Coleman's office said he had been assured the deployment that included Corporal Hughes had been sufficiently trained.